Client Proxy generated for wsdl with minOccurs=0 for value types.

Hi,
I have a wsdl file that I am migrating from the old netframework "svcutil" tool to the new "dotnet-svcutil" tool.

The old tool use to create client proxy methods with an additional "Specified" parameter for parameters that are value types, and are marked as optional (minOccurs=0) in the wsdl. The new tool doesn't seem to create the additional "Specified" parameter, so its not possible to call the webservice with the parameter "not specified".

Specifically, I am referring to a wsdl file from a VMWare SDK (VimService.wsdl), and an example method that gets generated in the proxy code is...

Old:
`public VimApi.PerfMetricId[] QueryAvailablePerfMetric(VimApi.ManagedObjectReference _this, VimApi.ManagedObjectReference entity, System.DateTime beginTime, bool beginTimeSpecified, System.DateTime endTime, bool endTimeSpecified, int intervalId, bool intervalIdSpecified)`

New:
`public VimApi.PerfMetricId[] QueryAvailablePerfMetric(VimApi.ManagedObjectReference _this, VimApi.ManagedObjectReference entity, System.DateTime beginTime, System.DateTime endTime, int intervalId)`

I'm specifying the following parameters when running the dotnet-svcutil tool:
`--serializer XmlSerializer --sync --targetFramework netstandard2.0 --namespace *,VimApi`

I have not included the original wsdl file in this initial report as it is large, and I'm not sure if its needed to reproduce the issue.